1. Field of the Invention
The present invention relates to a method for aging a display apparatus and electronic equipment using the aging method.
2. Description of the Related Art
It has been known that the display properties of a self-luminous display apparatus are generally unstable at an initial stage of use due to various factors. Therefore, an aging process for continuously driving the display apparatus for a predetermined time till the unstable display properties of the display apparatus are stabilized is typically carried out in a factory after a manufacturing process.
For example, in a cathode ray tube display apparatus (CRT), the luminance property and the deflection property are extremely unstable in an initial stage of use. In manufacturing the CRT, therefore, an aging process is carried out in the stage where respective parts and circuit boards have been set, so that the fluorescent screen of the CRT is controlled to display a full white screen with high luminance before video adjustment. This aging process is continuously performed till an output close to a set value can be obtained stably in response to a set input.
Also in a plasma display panel apparatus (PDP), a large variation in the luminescent property and the discharge property in an initial stage of use appears with the passage of time. Therefore, an aging process for driving the PDP for a predetermined time is carried out to stabilize the luminescent property and the discharge property. It is considered that the variation in properties of the PDP in an initial stage of use is caused by the influence of impurity gas staying behind in the discharge space after evacuation and by the fact that the surface state of a protective layer (MgO layer) facing the discharge space and having a function as a cathode for discharge changes in the initial stage. Accordingly, the process time of the aging process in the PDP is set in consideration of the time required for releasing/removing the impurity gas by the effect of discharge plasma to thereby clean the discharge space and in consideration of the time for the surface change of the protective layer to converge.
Many kinds of self-luminous display apparatus have been developed in recent years. In some of them, the luminance for a fixed input deteriorates conspicuously in an initial stage of use. In the display apparatus showing such properties, there arises problems different from the problem caused by the CRT or PDP in the initial stage, as follows.
That is, when light emitting devices disposed as components of the display apparatus are partially turned on and partially turned off in an initial stage of use in accordance with a pattern to be displayed on the screen, there occurs a large difference in luminance between the turned-on light emitting devices and the turned-off light emitting devices. Thus, there occurs a phenomenon that this difference results in the image persistence of the pattern staying on the display screen for some time. This phenomenon appears conspicuously particularly when a static image having a fixed pattern is displayed in an initial stage of use.
In addition, also when the display apparatus is a full-color or area-color display apparatus in which light emitting devices of respective colors of R, G and B have been arrayed, there occurs a similar image persistence phenomenon. In such a color display apparatus, the degree of deterioration in one of the colors in an initial stage of use often differs from that in another color. As a result, there is a problem that there occurs an image persistence phenomenon further including color unevenness.
To cope with such problems, it can be considered to still carry out an aging process in an initial stage of use in the same manner as in the display apparatus described above. However, in the present circumstances, there is no particular investigation made into the method for setting the process time or driving the apparatus for the aging process, and no aging process required for avoiding the image persistence phenomenon is carried out. Further, when the process time is set to be longer than necessary, the management time in a manufacturing factory increases. It is therefore considered that there is another problem that the manufacturing cost increases.
Further, particularly in an organic EL display apparatus, it has been confirmed that the degree of deterioration in luminance in an initial stage of use varies in accordance with the kind of luminescent material forming light emitting devices. In the present circumstances, material selection is made to avoid materials that deteriorate extremely and conspicuously in luminance in an initial stage of use, in order to prevent the image persistence phenomenon. However, with such material selection, materials having good progress of luminance in a stable stage or materials showing excellent properties for other factors such as a luminescent property or a coloring property cannot be selected. Thus, there occurs a problem that the range of material selection is narrowed in the material design for improving the display performance as a whole.